A stent may be loaded onto a catheter inner tube either from the distal end of the inner tube or from the proximal end of the inner tube. When the stent is loaded from the distal direction, however, the tip of the catheter may interfere with the stent. To avoid obstruction from the tip, the stent as loaded must have an opening wide enough to allow passage of the tip therethrough which causes issues in device performance. When the stent is loaded from the proximal direction, the stent may be obstructed by any proximal bumpers present on the inner tube. Typically, a bumper is provided proximal to the stent receiving region of the catheter inner tube to aid in delivering the stent from the catheter. To avoid obstruction from the bumper, the stent as loaded must have an opening wide enough to allow passage of the bumper therethrough, again causing issues with device performance.
Once the stent has been loaded on the catheter, a retractable sheath is typically placed over the stent. A number of devices for retracting a retractable sheath are known in the art. Patents disclosing retractable sheaths include U.S. Pat. No. 5,772,669 and U.S. Pat. No. 5,868,755. With many retraction systems, it is necessary to move a portion of the manifold by a distance at least equal to the length of the loaded stent to retract the sheath.
While a number of patents such as U.S. Pat. No. 6,090,035, U.S. Pat. No. 6,018,857 and U.S. Pat. No. 5,911,452 have dealt with the issue of stent loading, there remains a need for innovative methods of loading self-expanding stents onto catheters as well as for innovative catheters that facilitate this stent loading. There also remains a need for innovative catheters having retractable sheaths and sheath retraction mechanisms having a mechanical advantage to facilitate sheath retraction.
All US patents, patent applications and other published documents mentioned anywhere in this application are incorporated herein by reference in their entirety.
Without limiting the scope of the invention, a brief summary of various embodiments of the invention is set forth below. Additional details of the summarized embodiments of the invention and/or additional embodiments of the invention may be found in the Detailed Description of the Invention below.
A brief abstract of the technical disclosure in the specification is provided as well only for the purposes of complying with 37 C.F.R. 1.72. The abstract is not intended to be used for interpreting the scope of the claims.
In one embodiment, the present invention is directed to a stent delivery system comprising an inner tube having a proximal end and a distal end, a stent receiving region and a stent disposed about the stent receiving region of the inner tube. The delivery system further comprises a shape memory metal bumper disposed about the inner tube at a position adjacent the proximal or distal end of the stent. Desirably, the stent receiving region is at the distal end of the inner tube and the shape memory bumper is adjacent the proximal end of the stent.
The present invention is also directed in another embodiment to a delivery system for delivering an implantable medical device to a bodily lumen. The delivery system comprises an inner tube having a proximal end, a distal end and a medical device receiving region. An implantable medical device is disposed about the medical device receiving region of the inner tube. A shape memory metal bumper is disposed about the inner tube at a position adjacent the proximal or distal end of the implantable medical device. Desirably, the medical device receiving region is adjacent to the distal end of the inner tube and the shape memory bumper is adjacent the proximal end of the implantable medical device.
The present invention is further directed to a device delivery system comprising an inner tube having a proximal end, a distal end and a medical device receiving region. Desirably, the medical device receiving region is adjacent to the distal end of the inner tube. An implantable medical device is disposed about the medical device receiving region of the inner tube. A shape memory metal bumper is disposed about the inner tube at a position adjacent to the distal end or more desirably, the proximal end of the implantable medical device. The shape memory metal bumper is transformable between a martensitic state and an austenitic state. In the martensitic state, the shape memory metal bumper has a reduced profile. In the austenitic state, the shape memory metal bumper has an increased profile.
The present invention is also directed to a method of preparing a stent delivery system. In accordance with the inventive method, a tube having a proximal end and a distal end is provided. The distal end of the tube terminates in an enlarged tip. The tube has a bumper formed of a shape memory metal proximal to the tip. The bumper is expandable from a reduced profile state to an increased profile state. The bumper is in the reduced profile state. A stent having a flow passage therethrough sized to allow passage of the bumper therethrough when the bumper is in the reduced profile state is provided. The stent is passed about the bumper and the stent disposed about the inner tube adjacent to the bumper, between the bumper and the tip. Finally, the bumper is caused to transition from the reduced profile state to the increased profile state.
In another embodiment, the invention is directed to a medical device delivery system comprising a manifold having a rack and pinion. An inner tube extends distally from the manifold. A retractable sheath is disposed about the distal end of the inner tube. A pull-wire extends proximally from the retractable sheath to the manifold. The pull wire is attached to the pinion. The sheath may be retracted by moving one of the rack and pinion relative to the other.